I have had my wp40 for about 9 months and it started stopping on me so I cleaned it but it happened again so I emailed fish street and they sent me a new unit for shipping costs. just an FYI
If you go to their website there is a contact form and you fill it out and they email you back. Takes a little while due to the time difference but there are pretty responsive. Did you buy it from fish street? If not you may have to contact Jaebo and I have not heard good things about their customer service...